Climate change-related droughts have resulted in a significant drop in water levels on Lake Kariba to the point where there is no longer enough water for hydropower generation. The lake, which is shared by Zambia and Zimbabwe, is on the Zambezi river, one of Africa’s main rivers whose catchment areas have suffered from climate change-related droughts over the past few years.
The southern African region is currently reeling from the effects of a severe El Nino-induced drought. These droughts and heightened evaporation from increased heat have caused the lake’s water levels to drop to record lows.
As of this week, the lake’s live water storage (water available for power generation) had dropped to just 8 per cent, resulting in Zambia announcing that the powerplant on its side of the lake will be shut on September 14, 2024.
A statement from the Zambia Electricity Supply Corporation (ZESCO) said the water supply situation had become critically low, forcing it to start plans to shut down its power plant on the lake.
Kariba has two hydropower plants, the 1,080-megawatt (MW) Kariba North Bank Power Station operated by Zambia and the 1,050 MW Kariba South Bank Power Station operated by the Zimbabwe Power Company.
This is the second time power generation had to be stopped on the world’s largest artificial lake since it was created in 1959. The first time was in November 2022, when power generation was stopped on the Zimbabwean side due to low water levels.
Power generation on Kariba is designed to operate in the top 13 metres of the lake, between levels 475.5 metres and 488.5 m (with 0.7 m freeboard). It is these 13 metres of water that is on the cusp of depletion, making power generation impossible.
8% useable storage of water left
The Zambezi River Authority (ZRA), a bi-national body that manages the water resources on the shared lake, said that as of August 26, 2024, the lake’s live storage (the water available for power generation) had dropped from its design operating capacity of 13 metres to just 1.26 metres.
“The lake level is steadily decreasing due to low inflow, closing the period under review at 476.76m (8.71 per cent usable storage) on August 26, 2024,” the authority noted in its weekly report.
Because of the critical fall in the lake’s live storage, power generation on the Zambia side has been reduced to just 98 MW, while that on the Zimbabwean plant has fallen to 214 MW.
With the rains still some three months away, experts said the Zimbabwean plant is also expected to stop power generation later in the year. The lake’s record lowest live storage of 475.60 metres (about 0.8 per cent usable storage or just 10 cm above the minimum operating level) was recorded on December 30, 2022.
This has thrown the two southern African nations that primarily depend on Kariba for electricity into severe energy crisis that has seen Zambia increasing daily powercuts to 20 hours, while in Zimbabwe the powercuts now extend beyond 12 hours.
Powercuts worsen in Zambia
ZESCO spokesperson Matongo Maumbi warned Zambia to anticipate significant powercuts into the future as the country’s power deficit was 1,086 MW for August and was projected to increase to 1,280 MW in September.
“While the imports are critical, they may not be sufficient to fully balance supply and demand,” Maumbi said, adding that “emergency power rationing remains a possibility, and ZESCO is exploring all available options to stabilise the situation”.
While Zambia’s installed power generation capacity of 3,456.8 MW is more than its electricity peak demand of 2,300 MW, the country is vulnerable to climate shocks as 83 per cent of this electricity comes from hydropower sources. In addition to Kariba, Zambia relies on three other hydro plants that have also been severely crippled by climate change-related droughts.
These are Kafue Gorge (producing 372 MW against an installed capacity of 990 MW), Lower Kafue Gorge delivering 179 MW against an installed capacity of 750 MW and Itezhi-Tezhi Power Company that is generating just 34 MW against its installed capacity of 120 MW. The rest of the country’s power mix include 9 per cent from coal, 5 per cent from heavy fuel oil and 3 per cent from solar.
Solution in widening energy mix
The latest crisis has forced Zambia to hurry towards widening its power mix to include solar and other forms of renewable energy.
Zambian energy expert Johnstone Chikwanda said the solution for this southern African country, which requires a reliable power supply for its copper mines, is to diversify its energy mix.
“To improve the balancing of different energy sources, we are expected to drive the renewable energy pathway on a very serious note,” Chikwanda told Down To Earth. “Going forward and in terms of the road map established by the Integrated Resource Place (IRP) for the energy sector, we expect to continue diversifying the electricity generation sources in order to enhance security of supply,” he added.
In July, the country revealed plans for the construction of a new 300 MW coal powerplant at a cost of $400 million. This will bring Zambia’s total power from coal to 600 MW.
Chikwanda justified the decision as necessitated by the situation on the ground. “In addition, we have decided, as a country, to add another 300 MW of coal-fired powerplant (because) due to storage challenges, solar energy cannot be fully relied upon,” he said.
Zambian climate expert Idah Phiri told DTE that climate change is now affecting the lives of ordinary Zambians in a serious way. “Due to climate change, Zambia has experienced the worst drought ever, which has affected a number of sectors and worst-hit are the energy and water sectors,” Phiri said.
The country has experienced reduced groundwater levels as well as surface water, whereas our largest water reservoir, which generates a large percentage of electricity, is poised for shutdown and there’s no way out unless we have early rains.
Zambian climate expert Idah Phiri
She said the effects are being especially felt in the southern part of country, including capital city Lusaka and other major cities, which are heavily affected by powercuts with a heavy toll on the people’s daily income. “Small businesses that can’t afford alternative sources of energy are barely managing to survive, and if the power generation is completely shut, the negative impacts will be far worse.”
Similar crisis in Zimbabwe
After losing more than 800 MW of power at Kariba, Zimbabwe also faces powercuts of up to 12 hours. Its peak electricity demand is about 2,200 MW, while supply stands at 1,206 MW. The bulk of this electricity comes from its ageing thermal-fired power station in Hwange.
“The stored capacity at Kariba is 1,050 megawatts and we are only able to produce 214 megawatts on average because of the water rationing that has resulted out of low inflows in the lake,” energy minister Edgar Moyo told the parliament. “On that perspective, after losing over 800 megawatts, it makes it very difficult to sufficiently supply power in the country.”
The country is also moving towards solar energy resources, with the country signing up power generation deals for more than 2,000 MW of electricity from solar.
